This patent application claims priority based on a Japanese patent application, 2000-533 filed on Jan. 5, 2000, the contents of which are incorporated herein by reference.
The present invention relates to a cam mechanism. More specifically, the invention is directed to a cam mechanism that is operable with pop-up devices, such as a flash device, LCD monitor, or other similar devices.
Cameras typically include flash mechanisms, which generally can be extended from the body of a camera by a pop-up mechanism for operation of the flash during photography. An example of a pop-up device, in which the flash part moves between a retracted position and an extended position by operation of a rotary lever, is disclosed in a Japanese Patent Publication No. Hei. 4-17402 published in 1992.
It has, however, been found that use of a pop-up mechanism in photographic devices results in a gap between the casing of the photographic device and the pop-up part due to the pop-up part not being fully retained in the casing by the pop-up mechanism. Further, miniaturization of photographic devices is desirable, but conventional pop-up mechanisms tend to be relatively large in size thereby hindering miniaturization.
Accordingly, it would be desirable to provide an improved pop-up mechanism for extending and retracting pop-up parts, such as flash mechanisms, LCD displays, and the like, with the pop-up mechanism facilitating miniaturization, while having robust functionality.
The difficulties and limitations suggested in the preceding are not intended to be exhaustive, but rather are among many which demonstrate that prior art pop-up mechanisms of the type described herein will admit to worthwhile improvement.
It is, therefore, a general object of the invention to provide an improved pop-up mechanism, which will obviate or minimize difficulties of the type previously described.
It is a specific object of the invention to provide a cam mechanism operable with a pop-up device.
It is another specific object of the invention to provide a cam mechanism which is easy to assemble.
It is yet another specific object of the invention to provide a cam mechanism which facilitates miniaturization.
It is yet another specific object of the invention to provide a cam mechanism having substantially planar parts that move substantially in one plane and in a direction perpendicular to the plane.
It is yet another specific object of the invention to provide a cam mechanism having relatively few parts, while providing robust functionality.
A cam mechanism operable to achieve at least some of the foregoing objects includes a cam member for movement substantially in a first plane and a lock member for movement substantially in the first plane when the cam member moves from a first position to a second position. The lock member retains the cam member at a predetermined position and releases the cam member by movement of the lock member in a direction substantially perpendicular to the first plane.
The cam mechanism also includes a first spring for moving the lock member to a position for retaining the cam member and a second spring for moving the cam member, wherein the lock member restricts movement of the cam member caused by the second spring. Furthermore, the cam mechanism includes a third spring for moving the lock member in an opposite direction to the perpendicular direction.
Preferably, the first spring and the third spring are formed integrally as a torsion spring with one end of the torsion spring causing the lock member to move in the first plane, and the other end of the torsion spring causing the lock member to move in the opposite direction to the perpendicular direction. When the cam member is moved in the opposite direction to the movement by the second spring, with the restriction of the movement of the cam member being released, the lock member is moved in substantially in the first plane in the opposite direction to the movement caused by the first spring.
The cam mechanism further includes a first axis for supporting the lock member in a rotatable way and a second axis for supporting the cam member in a rotatable way, wherein the first spring causes movement of the lock member in a first rotary direction about the first axis and the second spring causes movement of the cam member in a second rotary direction about the second axis.
Preferably, the lock member includes a through-hole for receiving the first axis and a gap, sufficient for movement of more than one part of the lock member towards an axis, is provided between the lock member and the first axis. A collar is provided at the first axis having a diameter greater than the diameter of the through-hole to retain through-hole from movement along the axis.
Preferably, the cam member includes a guide part formed in a surface thereof parallel with the first plane and the lock member is urged toward a track where the lock member is moved by the guide part. Preferably, a convex part is provided to protrude in a perpendicular direction to the first plane and disposed on one side of contacting portions of the lock member and the cam member. Preferably, the lock member includes an engaging part for engaging with the cam member, and the cam member is retained by the engaging part being moved by the first spring when the cam member reaches a predetermined position. More preferably, the engaging part causes the cam member to move in an opposite direction to the direction of the movement caused by the second spring when the engaging part retains the cam member by being moved by the first spring.
Preferably, a range of movement of the cam member is limited to between a first position of the cam member when the cam member is released for movement and a second position of the cam member when the lock member engages therewith.
Preferably, the cam mechanism further includes a spring support part for charging and supporting the second spring for the second spring to move the cam member. Preferably, a combination of a cam mechanism according to the invention and a device having a pop-up part, such as a camera, is provided.